Biometric system for biometric input, comparison, authentication and access control and method therefor

A biometric input device, system and method includes a biometric input device having a scanning window disposed in a side of a device body so as to facilitate positioning of a biometric sample such as a thumb. The biometric input device further includes a guide assembly in the form a ridge disposed about a periphery of a scanning surface so as to effectively align and guide the thumb onto the scanning surface and so as to prevent ambient light from entering the scanning surface an interfering with the generation of a light image.